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United States Patent |
5,104,200
|
Prout
,   et al.
|
April 14, 1992
|
Heavy-duty blow-molded wheel and roll-out waste container with
heavy-duty blow-molded wheel
Abstract
A heavy-duty, wear resistent, blow-molded plastic wheel comprising a
circular web defining a central axle bore, an integrally-formed
radially-extending peripheral side wall, and an integrally-formed,
axially-extending tread, the side wall having a width no greater than
one-fourth the width of the tread. A roll-out type, plastic waste
container having a waste-receiving container body, a handle, a lifting bar
and wheel mounts is provided in combination with a heavy-duty, wear
resistant, blow-molded plastic wheel as described above mounted on the
wheel mounts.
Inventors:
|
Prout; John T. (Winston-Salem, NC);
Cagle; Billy R. (Mooresville, NC)
|
Assignee:
|
Toter, Inc. (Statesville, NC)
|
Appl. No.:
|
549369 |
Filed:
|
July 6, 1990 |
Current U.S. Class: |
301/64.705 |
Intern'l Class: |
B60B 005/02; B60B 003/12 |
Field of Search: |
301/63 PW,63 DD,64 R,64 SH,5 R
152/323
|
References Cited
U.S. Patent Documents
1102193 | Jun., 1914 | Horn et al. | 301/64.
|
1420337 | Jun., 1922 | Palmer | 301/63.
|
1470742 | Oct., 1923 | Ibach | 301/64.
|
1586425 | May., 1926 | Goodyear | 301/63.
|
1599845 | Sep., 1926 | Shoemaker | 301/63.
|
2629420 | Feb., 1953 | Walklet | 301/63.
|
3977454 | Aug., 1976 | Coran et al. | 301/63.
|
4444435 | Apr., 1984 | Honsa | 301/63.
|
4674759 | Jun., 1987 | Parker | 301/63.
|
Foreign Patent Documents |
219469 | Apr., 1957 | AU | 301/63.
|
13859 | Jul., 1899 | GB | 301/64.
|
Primary Examiner: Stormer; Russell D.
Attorney, Agent or Firm: Adams, III.; W. Thad
Claims
I claim:
1. A heavy-duty integrally formed wear resistent, blow-molded plastic wheel
comprising:
(a) an integrally-formed circular web defining a central axle bore;
(b) two radially extending peripheral side walls having a plurality of
axially spaced-apart spokes alternating with a plurality of axially-joined
webs of increased pressure resistance extending radially outwardly from
adjacent the axle bore;
(c) an axially extending tread integrally formed with said side walls and
connecting said side walls around the peripheral edge of the wheel;
(d) said side walls adjoining the tread in the area of the axially-joined
webs having a radial width no greater than one-forth the width of the
tread to reduce compression to the tread area of the wheel when the wheel
is under extreme loads.
2. A heavy-duty blow-molded wheel according to claim 1, wherein said wheel
includes a plurality of radially-outwardly extending, spaced-apart spokes
having a pre-determined thickness and separated by web portions having a
thickness less than the thickness of the spokes to define relief areas
between said spokes.
3. A heavy-duty blow-molded wheel according to claim 2, wherein said web
portions are normal to the plane of the tread.
4. A heavy-duty blow-molded wheel according to claim 1, wherein said wheel
includes a plurality of integrally-formed and spaced-apart stiffening lugs
adjacent said side wall and projecting inwardly towards the axle-bore.
5. A heavy-duty blow-molded wheel according to claim 1, wherein said side
wall has a width no greater than one-sixth the width of the tread.
6. A heavy-duty blow-molded wheel according to claim 1 or 5, wherein said
side wall is approximately one-quarter inch (6 mm) in width and said tread
is approximately one-and-three-quarters (44 mm) inches in width.
7. A heavy-duty blow-molded wheel according to claim 1 or 5, wherein said
wheel includes five outwardly-extending, relatively thick spokes separated
by five web portions of reduced thickness.
8. A heavy-duty blow-molded wheel according to claim 7, wherein said wheel
includes a five integrally-formed and spaced-apart stiffening lugs
adjacent said side wall and projecting inwardly towards the axle-bore in
alternate web portions.
9. A heavy-duty blow-molded wheel according to claim 1 or 5, wherein said
side wall and said tread define an enclosed hollow area.
10. A heavy-duty blow-molded wheel according to claim 1 or 5, wherein said
web surrounding said axle bore defines an enclosed hollow area.
11. A heavy-duty blow-molded wheel according to claim 1 or 5, wherein said
side wall and said tread define an enclosed hollow area and wherein said
web surrounding said axle bore defines an enclosed hollow area, each of
said hollow areas being generally triangular in cross-section
12. In a roll-out type, plastic waste container having a waste-receiving
container body, a handle, lifting means and wheel-mounting means, the
combination therewith of a heavy-duty, wear resistent, blow-molded plastic
wheel mounted on said wheel-mounting means and comprising:
(a) an integrally-formed circular web defining a central axle bore;
(b) two radially extending peripheral side walls having a plurality of
axially spaced-apart spokes alternating with a plurality of axially-joined
webs of increased pressure resistance extending radially outwardly from
adjacent the axle bore;
(c) an axially extending tread integrally formed with said side walls and
connecting said side walls around the peripheral edge of the wheel;
(d) said side walls adjoining the tread in the area of the axially-joined
webs having a radial width no greater than one-forth the width of the
tread to reduce compression to the tread area of the wheel when the wheel
is under extreme loads.
13. In a waste container according to claim 12, wherein said wheel includes
a plurality of radially-outwardly extending, spaced-apart spokes having a
pre-determined thickness and separated by web portions having a thickness
less than the thickness of the spokes to define relief areas between said
spokes.
14. In a waste container according to claim 13, wherein said web portions
are normal to the plane of the tread.
15. In a roll-out type, plastic waste container according to claim 12,
wherein said wheel includes a plurality of integrally-formed and
spaced-apart stiffening lugs adjacent said side wall and projecting
inwardly towards the axle-bore.
16. In a waste container according to claim 12, wherein said side wall has
a width no greater than one-sixth the width of the tread.
17. In a waste container according to claim 12 or 16, wherein said side
wall is approximately one-quarter inch (6 mm) in width and said tread is
approximately one-and-three-quarters inches (44) in width.
18. In a waste container according to claim 12 or 16, wherein said wheel
includes five outwardly-extending, relatively thick spokes separated by
five web portions of reduced thickness.
19. In a waste container according to claim 18, wherein said wheel includes
a five integrally-formed and spaced-apart stiffening lugs adjacent said
side wall and projecting inwardly towards the axle-bore in alternate web
portions.
20. In a waste container according to claim 12 or 16, wherein said side
wall and said tread define an enclosed hollow area.
21. In a waste container according to claim 12 or 16, wherein said web
surrounding said axle bore defines an enclosed hollow area.
22. In a waste container according to claim 12 or 16, wherein said side
wall and said tread define an enclosed hollow area and wherein said web
surrounding said axle bore defines an enclosed hollow area, each of said
hollow areas being generally triangular in cross-section.
Description
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION
This invention relates to a heavy duty blow molded wheel adaptable for many
purposes but described in this application for particular use with a
roll-out waste container of the type commonly used by waste haulers and
municipalities for "street-side" waste collection.
One-piece molded plastic wheels are known in the prior art. However, prior
art wheels are designed to resemble older-type pneumatic or semi-pneumatic
wheels. Generally, this means that the side wall and tread portions of the
plastic wheel are designed to resemble the rubber tire portion of a
pneumatic or semi-pneumatic wheel, included a rounded tread area and a
rounded, relatively thick width side wall.
There are, of course, reasons why a pneumatic tire has a rounded tread and
side wall cross-section. Since the tire is filled with pressurized air,
the tire will naturally want to assume a rounded cross-section since the
air is pressing with equal force on all interior parts of the tire.
Furthermore, since a pneumatic tire is designed to compress under weight
and to absorb and cushion irregularities in the rolling surface, a
relatively thick width side wall is required so that the tire will not be
compressed to the point where the tread bottoms out on the wheel rim under
heavy impact or weight loads. In other words, the side wall needs to be
benefits offered by pneumatic and semi-pneumatic rubber tires.
These considerations to not apply in the use of plastic wheels. Plastic
wheels are relatively stiff and brittle in comparison to rubber tires. Of
course, plastic wheels are not pneumatic. They are generally used in
situations where loads are not great, and on relatively even surfaces
where it is not necessary to cushion impact on the wheel, for example on
roll-out waste containers.
However, roll-out waste containers are becoming larger and are designed to
carry much heavier loads. For these reasons, conventionally designed
plastic wheels are now subject to crushing due to heavy loads placed on
them. This crushing usually occurs in the side-wall area, which has a
relatively thin cross-sectional dimension. Since the side wall area is
generally perpendicular, or normal, to the direction of load application,
the side walls are caused to bulge out under load. The relatively brittle
plastic is not designed to flex to any substantial degree, and for this
reason the side wall breaks down, damaging the wheel and eventually
requiring replacement.
Of course, the cross-sectional thickness of the side wall can be made
progressively greater to withstand heavier loads, or the volume occupied
by the side walls and the tread could even be made nearly or completely
solid. However, this complicates the molding process, uses more plastic
material, and results in a heavier wheel.
It has been discovered that a wheel which will withstand heavy-duty loads
without damage can be made using no more or even less material by
substantially reducing the width of the side walls in proportion to the
width of the wheel tread. The width of the side wall is therefore
substantially smaller in relation to its own cross-sectional thickness,
and the side wall is able to withstand much greater loads.
SUMMARY OF THE INVENTION
Therefore, it is an object of the invention to provide a heavy-duty
blow-molded wheel having a crush-resistent side wall area.
It is another object of the invention to provide a heavy-duty blow-molded
wheel which has a side wall cross-sectional thickness which is relatively
large in relation to its width.
It is another object of the invention to provide an integrally-formed one
piece blow molded wheel which has a side wall cross-sectional thickness
which is relatively large in relation to its width.
These and other objects of the present invention are achieved in the
preferred embodiments disclosed below by providing a heavy-duty, wear
resistent, blow-molded plastic wheel comprising a circular web defining a
central axle bore, an integrally-formed radially-extending peripheral side
wall, and an integrally-formed, axially-extending tread, the side wall
having a width no greater than one-fourth the width of the tread.
According to one preferred embodiment of the invention, the wheel includes
a plurality of radially-outwardly extending, spaced-apart spokes having a
pre-determined thickness and separated by web portions having a thickness
less than the thickness of the spokes to define relief areas between the
spokes.
According to another preferred embodiment of the invention, the wheel
includes a plurality of integrally-formed and spaced-apart stiffening lugs
adjacent the side wall and projecting inwardly towards the axle-bore.
According to yet another preferred embodiment of the invention, the side
wall has a width no greater than one-sixth the width of the tread.
According to one preferred embodiment of the invention, the side wall is
approximately one-quarter inch (6 mm) in width and the tread is
approximately one-and-three-quarters inch (44 mm) in width.
According to another preferred embodiment of the invention, the wheel
includes five outwardly-extending, relatively thick spokes separated by
five web portions of reduced thickness.
Preferably, the wheel includes a five integrally-formed and spaced-apart
stiffening lugs adjacent the side wall and projecting inwardly towards the
axle-bore in alternate web portions.
Preferably, the web portions are normal to the plane of the tread.
According to one preferred embodiment of the invention, the side wall and
the tread define an enclosed hollow area.
According to yet another preferred embodiment of the invention, the web
surrounding the axle bore defines an enclosed hollow area.
According to one preferred embodiment of the invention, the side wall and
the tread define an enclosed hollow area and wherein the web surrounding
the axle bore defines an enclosed hollow area, each of the hollow areas
being generally triangular in cross-section.
According to another preferred embodiment of the invention, a roll-out
type, plastic waste container having a waste-receiving container body, a
handle, lifting means and wheel-mounting means is provided in combination
with a heavy-duty, wear resistent, blow-molded plastic wheel mounted on
the wheel-mounting means and comprising, a circular web defining a central
axle bore, an integrally-formed radially-extending peripheral side wall,
and an integrally-formed, axially-extending tread, the side wall having a
width no greater than one-fourth the width of the tread.
According to yet other preferred embodiments of the invention, the other
features of the blow-molded wheel as described above are combined with the
roll-out cart.
BRIEF DESCRIPTION OF THE DRAWINGS
Some of the objects of the invention have been set forth above. Other
objects and advantages of the invention will appear as the invention
proceeds when taken in conjunction with the following drawings, in which:
FIGS. 1 and 2 are roll-out type waste containers having a blow-molded wheel
according to an embodiment of the invention mounted thereon;
FIG. 3 is a perspective view of the blow-molded wheel according to an
embodiment of the invention;
FIG. 4 is a plan view of the blow molded wheel shown in FIG. 3;
FIG. 5 is a cross-section of the wheel shown in FIGS. 3 and 4 taken
substantially along lines 5--5 of FIG. 4; and
FIGS. 6 and 7 are cross-sections of the wheel shown in FIGS. 3 and 4 taken
substantially along lines 6--6 and 7--7 of FIG. 4, respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENT AND BEST MODE
Referring now specifically to the drawings, a roll-out type waste container
mounted with blow-molded wheels according to the present invention is
illustrated in FIGS. 1 and 2, and shown generally at reference numeral 10.
Container 10 has a container body 11 with a top opening 12. The container
10 is maneuvered by a handle 13 molded into the container 10, and as is
shown in FIG. 1, a lifting bar 15 which cooperates with a lifting hook
carried on a lifting mechanism of the type usually carried by a waste
collection vehicle.
Container 10 is mounted on a pair of wheels 30 according to the present
invention. Referring now to FIGS. 3-5, the wheel 30 is illustrated. Wheel
30 is blow-molded of high molecular weight polyethylene of a type
particularly suited for blow molding. Wheel 30 is blow-molded in a single,
integrally-formed piece with a part line (not shown) extending around the
periphery of the wheel 30 equidistant the two side-edges of a tread 31.
The term tread is used even though the rolling surface of the tread 31 is
relatively smooth. If desired, some form of texture could be imparted to
the tread 31.
Wheel 30 according to the particular design shown in the drawings has five
single thickness webs 32 alternating with five relatively thick hollow
spokes 33, converging on the center of wheel 30 to define an axle bore 34,
and diverging to define the tread 31 and a narrow width side wall 35 which
extends around the periphery of wheel 30 in a plane substantially parallel
to the plane of webs 32 and spokes 33, and normal to the plane of the
tread 31.
Stiffening lugs 36 are molded into the webs 32 to provide stiffening
re-enforcement to wheel 30. Preferably, the blow pin is inserted through
one of the stiffening lugs 36. Both sides of wheel 30 are structurally and
visually the same.
The dimensions referred to below are for a ten inch (25 cm) diameter wheel
30 having a five-eights inch (16 mm) axle bore 34. The spokes 33 have a
height above the adjacent webs 32 of three-quarter inch (19 mm).
Referring more specifically to the side wall 35, the width of the side wall
35 is quite small in comparison with the thickness of its cross-section,
and also quite small in comparison with the width of the tread 31. See
FIGS. 5 and 6, which also shows the cross-sectional geometry of the wheel.
For example, in a conventional rubber tire or molded plastic wheel the
width of the side wall may be equal to or greater than the width of the
tread. In contrast, in the wheel 30 according to the preferred embodiment
shown in the drawings, side wall 35 has a width of only one-quarter inch
(6 mm), whereas the width of the tread 31 is one and three-quarters inches
(44 mm). In other words, the width of the side wall 35 is only about
one-seventh the width of the tread 31.
While variations are possible depending on the geometry of the wheel, the
material from which the wheel is molded and the like, it is believed that
highly improved wear and resistance to crushing due to loading can be
achieved by limiting the width of the side wall to no more than one-fourth
the width of the tread. For example, in a wheel having a two inch (50 mm)
wide tread, the side wall should preferably be about one-quarter inch (6
mm) wide and preferably no more than about one-half inch (12 mm) wide.
The cross-sectional thickness of the side wall portion of wheel 30 is
approximately one-eighth inch (3 mm). A change in the diameter of the
wheel 30 would require a proportional change in the dimensions set out
above, but not in the ratios of side wall width and tread width described
above.
A heavy-duty blow-molded wheel and a roll-out type waste container mounted
on a heavy duty blow-molded wheel are described above. Various details of
the invention may be changed without departing from its scope.
Furthermore, the foregoing description of the preferred embodiment of the
invention and the best mode for practicing the invention are provided for
the purpose of illustration only and not for the purpose of
limitation--the invention being defined by the claims.
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